Viologen-based electrochromic materials and devices
Considerable interest is raised by organic materials owing to their exceptional performance in electronic and optoelectronic applications. Among these, electrochromic materials (EC) that can be switched between a distinct color and a bleached state exhibiting high contrast, multicolor and improved l...
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| Published in | Journal of materials chemistry. C, Materials for optical and electronic devices Vol. 7; no. 16; pp. 4622 - 4637 |
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| Main Authors | , , , , |
| Format | Journal Article |
| Language | English |
| Published |
Cambridge
Royal Society of Chemistry
2019
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| Subjects | |
| Online Access | Get full text |
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| Summary: | Considerable interest is raised by organic materials owing to their exceptional performance in electronic and optoelectronic applications. Among these, electrochromic materials (EC) that can be switched between a distinct color and a bleached state exhibiting high contrast, multicolor and improved long-term stability are attractive in the fabrication of electrochromic devices (ECDs). Ionic materials, in particular, have received persistent attention owing to their tunable optical and electronic properties. 4,4′-Bipyridinium salts, commonly called viologens (V
2+
), are a well-recognized class of electrochromic materials that exhibit three reversible redox states, namely, V
2+
(dication, pale yellow colored/colorless) ↔ V
+
&z.rad; (radical cation, violet/blue/green) ↔ V
0
(neutral, colorless). The electrochromic properties of these materials can be modulated by varying the nitrogen substituents on the pyridyl 'N'; also, besides this, varying the counter ions with specific functionalities has been shown to enhance the electrochromic behavior, such as switching time, cycling stability and device performance. Although ECDs based on viologens are well regarded for their low operational voltages, they exhibit certain disadvantages such as low cycle life and poor efficiency of the device in the long term. Extensive efforts have been made to fine tune the EC properties of viologens, either through alteration or by adding suitable electrochromic counter electrode materials, which includes the incorporation of conducting polymers in the device set-up and/or the addition of complementary redox species. Optimization of the device parameters has shown that the addition of such external agents has a positive effect on the overall device performance. This review describes recent developments in the synthesis of viologen-based electrochromes with co-redox species and their ECD performance.
This review describes recent developments relating to the synthesis of viologen-based electrochromes with co-redox species and their ECD performance. |
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| Bibliography: | 2 reduction and conversion to useful organics, metal organic frameworks and porous organic polymers for energy-related applications. Dr David Velayutham graduated from Madurai Kamaraj University with both Bachelor's (1982) and Master's degrees (1984). He joined the CSIR-Central Electrochemical Research Institute (CSIR-CECRI) as a Junior Scientist in 1987 and received his PhD from Alagappa University, Karaikudi, India, in 1993. He then moved to the University of Duisburg, Germany as a Post-Doctoral Fellow (1994) for 18 months, after which he resumed his duties at CSIR-CECRI. He is currently working as a Chief Scientist in the Electro Organic Division, CSIR-CECRI, Karaikudi, TamilNadu, India. His current research interests include electro-organic synthesis, electrochemical fluorination and the synthesis of ionic liquids for electrochemical applications, including super capacitors and lithium ion batteries. Dr Murugavel Kathiresan graduated from the University of Madras with both Bachelor's (2004) and Master's degrees (2006), and received his PhD from the University of Osnabrück, Germany, in 2010 under the guidance of Prof. Lorenz Walder. He then moved to the University of Basel, Switzerland, to conduct his postdoctoral research with Prof. Marcel Mayor. He was awarded the DST-INSPIRE Faculty award in December 2013. From March 2014 to April 2017, he worked as a DST-INSPIRE faculty member at the Electro Organic Division, CSIR-Central Electro Chemical Research Institute, Karaikudi, India. Since April 2017, he has been working as a Scientist in the same department. His current research interests include viologen-based supramolecular chemistry, along with the investigation of their applications towards photophysical and biological applications, electro-organic synthesis, electrochemical CO Dr Vembu Suryanarayanan, received his BSc and MSc degrees from the Department of Chemistry, Bharathidasan University, Trichy, India, in 1990 and 1992, respectively. He received his PhD (Electrochemical Fluorination) from Alagappa University, Karaikudi, India, in 1998. He completed his postdoctoral studies at the National Taiwan University, Taiwan, and Utsunomiya University, Japan, from 2003 to 2006. He has published about 78 papers in peer-reviewed journals and contributed a chapter to Diamond Electrochemistry (ed. A. Fujishima, et al., Elsevier, 2005). Currently, he is working as a Principal Scientist in the Electro Organic Division, CSIR-Central Electrochemical Research Institute, Karaikudi, India. His research interests include the synthesis of novel ionic liquids as well as their applications in various electrochemical devices, and nanomaterial composites for electrochemical sensing. Dr Kuo-Chuan Ho received his Bachelor's and Master's degrees from the Department of Chemical Engineering, National Cheng Kung University, Taiwan, in 1978 and 1980, respectively. He received his PhD in Chemical Engineering from the University of Rochester, USA, in 1986. Currently, he is a Distinguished Professor jointly appointed by the Department of Chemical Engineering and Institute of Polymer Science and Engineering at the National Taiwan University. His research interests mainly encompass applications of chemically modified electrodes to sensing and electro-optical devices, including electrochromic devices and dye-sensitized solar cells. Kanagaraj Madasamy graduated from the University of Madras with both Bachelor's and Master's degrees, and is currently doing a PhD at CSIR-Central Electrochemical Research Institute, Karaikudi, India, under the guidance of Dr Velayutham and co-guidance of Dr M. Kathiresan. His research interests include the synthesis of organic compounds and metal organic frameworks, and supramolecular chemistry. He is currently working on viologen-based supramolecular self-assemblies. ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 |
| ISSN: | 2050-7526 2050-7534 |
| DOI: | 10.1039/c9tc00416e |